The present invention relates generally to the production of heat or energy, and more particularly to a technique and to a system for carrying out the technique which exploits ligneous or other wastes, such as wooden chips, sawdust or compacted household rubbish in order, for instance, to heat boilers producing hot water or steam.
The high price of fossil fuels such as coal and petroleum has in recent years stimulated research directed to the combustion of various industrial or agricultural wastes for heating purposes. Thus processes are known for producing heat by the combustion of ligneous wastes such as sawdust and other wood-cutting residues. These prior methods usually involve the removal of the wastes to be burned from a bin and their division or disintegration by crushing. The crushed waste material is then entrained in a stream of air and is directly injected into the mouth of a boiler where the wastes are ignited more or less spontaneously under the action of the heat radiated in the firebox.
In practice, however, the ignition of the waste injected in this manner is not entirely spontaneous, and the combustion is therefore frequently incomplete. It is for this reason that such prior processes also include the simultaneous injection of a more inflammable fuel such as petroleum or gas, the ligneous waste then serving as an auxiliary fuel. Hence prior techniques that dictate the use of costly and scarce fossil fuels as well as waste matter are inefficient in economic terms.